$9hi + 10hj - h - 9 = i + 7$ Solve for $h$.
Solution: Combine constant terms on the right. $9hi + 10hj - h - {9} = i + {7}$ $9hi + 10hj - h = i + {16}$ Notice that all the terms on the left-hand side of the equation have $h$ in them. $9{h}i + 10{h}j - 1{h} = i + 16$ Factor out the $h$ ${h} \cdot \left( 9i + 10j - 1 \right) = i + 16$ Isolate the $h$ $h \cdot \left( {9i + 10j - 1} \right) = i + 16$ $h = \dfrac{ i + 16 }{ {9i + 10j - 1} }$